Many types of filters and filter assemblies presently are available for removing suspending foreign matter from fluids such as lubricating oil, hydraulic fluids and the like. Various filters are used in hydraulic systems for aircraft in filtering hydraulic fluid in high pressure hydraulic fluid systems. Under such conditions, the filters must be serviced without external leakage when cleaning, servicing or maintenance is required, and which can be reassembled without external leakage from the system. Such filters of varying types employ removable cartridges whereby, when a filter cartridge becomes spent, the cartridge is readily replaceable with a fresh cartridge. Failure or inadvertent leakage or actuation of the fluid stream valve while the cartridge assembly and/or associated connections are removed can create undesirable conditions.
To overcome these problems, various-arrangements in the prior art provide for locking or latching the valves within the fluid stream to prevent accidental flow during replacement of the filter media. Many such arrangements are complex, cumbersome and can themselves become contaminated and cause undesirable leakage.
This invention is directed to solving the problem of fluid leakage in a removable cartridge-type filter by employing a novel seal means which performs the dual function of sealing the inlet fluid stream when a cartridge is removed and for providing a stop limit for movement of the sealing valve.